Ultrasonic welding systems, methods of using the same, and related workpieces including welded conductive pins

ABSTRACT

An ultrasonic welding system is provided. The ultrasonic welding system includes a support structure for supporting a workpiece. The ultrasonic welding system also includes a weld head assembly including an ultrasonic converter carrying a sonotrode. The ultrasonic welding system also includes a conductive pin supply configured to provide a plurality of conductive pins for welding using the sonotrode.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication No. 63/034,345 filed Jun. 3, 2020, the contents of which areincorporated herein by reference.

FIELD

The invention relates to the ultrasonic welding, and more particularly,to improved systems and methods for performing ultrasonic weldingoperations including conductive pin welding.

BACKGROUND

Ultrasonic energy is widely used in forming interconnections between twoor more materials. For examples, wire bonding machines (e.g., ballbonding machines, wedge bonding machines, ribbon bonding machines, etc.)are used to bond a wire or ribbon to a bonding location. However, wirebonding utilizes relatively low levels of energy (e.g., bond force,ultrasonic energy, etc.). Exemplary wire bonding machines are marketedby Kulicke and Soffa Industries, Inc. of Fort Washington, Pennsylvania.

Certain applications involve joining of materials other than wire.Welding has been considered for such applications. Ultrasonic welding isalso a widely used technology. Ultrasonic welding may use an ultrasonicconverter (e.g., carrying a sonotrode) for converting electrical energyinto mechanical movement/scrub (e.g., linear movement/scrub, torsionalmovement/scrub, etc.). However, existing ultrasonic welding technologyand equipment is limited in its ability to provide solutions that cansatisfy market demand in terms of cost, operational efficiency,flexibility, portability, and related factors.

International Publication No. 2018/187364 (entitled “Ultrasonic WeldingSystems and Methods of Using the Same”), assigned to Kulicke and SoffaIndustries, Inc., relates to improvements in ultrasonic weldingtechnology, and is incorporated by reference in its entirety.

Still, improvements are needed in connection with applications ofultrasonic welding, including ultrasonic pin welding (where such pinsare typically solder and/or press fit into power modules). Thus, itwould be desirable to improve ultrasonic welding technology includingultrasonic pin welding.

SUMMARY

According to another exemplary embodiment of the invention, anultrasonic welding system is provided. The ultrasonic welding systemincludes a support structure for supporting a workpiece. The ultrasonicwelding system also includes a weld head assembly including anultrasonic converter carrying a sonotrode. The ultrasonic welding systemalso includes a conductive pin supply configured to provide a pluralityof conductive pins for welding using the sonotrode.

According to yet another exemplary embodiment of the invention, a methodof operating an ultrasonic welding system is provided. The methodincludes the steps of: (a) supporting a workpiece on a support structureof the ultrasonic welding system; and (b) welding a conductive pin froma conductive pin supply of the ultrasonic welding system to theworkpiece using a sonotrode of a weld head assembly of the ultrasonicwelding system, the conductive pin supply including a plurality of theconductive pins.

According to yet another exemplary embodiment of the invention, aworkpiece is provided. The workpiece includes: a substrate; and aconductive pin ultrasonically welded to the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is best understood from the following detailed descriptionwhen read in connection with the accompanying drawings. It is emphasizedthat, according to common practice, the various features of the drawingsare not to scale. On the contrary, the dimensions of the variousfeatures are arbitrarily expanded or reduced for clarity. Included inthe drawings are the following figures:

FIG. 1 is a block diagram side view of an ultrasonic welding system inaccordance with an exemplary embodiment of the invention;

FIG. 2A is a block diagram side view of another ultrasonic weldingsystem in accordance with another exemplary embodiment of the invention;

FIG. 2B is a perspective view of a tip portion of a sonotrode of theultrasonic welding system of FIG. 2B;

FIG. 2C is a side view of a conductive pin from the conductive pinsupply of the ultrasonic welding system of FIG. 2B;

FIG. 3A is a block diagram side view of yet another ultrasonic weldingsystem in accordance with yet another exemplary embodiment of theinvention;

FIGS. 3B-3C are side block diagram views illustrating withdrawal of aconductive pin from a conductive pin supply using the ultrasonic weldingsystem of FIG. 3A;

FIG. 3D is a side view of a conductive pin from the conductive pinsupply of the ultrasonic welding system of FIG. 3A;

FIG. 4 is a block diagram side view of yet another ultrasonic weldingsystem in accordance with yet another exemplary embodiment of theinvention;

FIG. 5 is a block diagram side view of yet another ultrasonic weldingsystem in accordance with yet another exemplary embodiment of theinvention;

FIGS. 6A-6G are various views of conductive pins and sonotrodesillustrating alignment with keying features in accordance with variousexemplary embodiments of the invention; and

FIG. 7 . is a block diagram side view of an ultrasonic welding system inaccordance with an exemplary embodiment of the invention.

DETAILED DESCRIPTION

FIG. 1 illustrates an ultrasonic welding system 100. Ultrasonic weldingsystem 100 includes an input workpiece supply 102 for providing aworkpiece 102 a 1, where input workpiece supply 102 is configured tocarry a plurality of workpieces 102 a 1 (e.g., workpiece supply 102 maybe a carrier such as a magazine handler for carrying a plurality ofworkpieces 102 a 1, or other supply structure suitable for theapplication specific workpiece, etc.). Exemplary workpieces 102 a 1carried by input workpiece supply 102 include power modules, componentsof power modules, lead frames, battery modules, etc. Workpieces 102 a 1are provided (by any desired transport assembly which may be included ina material handling system 104, such as a gripper assembly) from inputworkpiece supply 102 to a material handling system 104. Materialhandling system 104 moves workpiece 102 a 1 (e.g., using a conveyorassembly, using a gripper assembly, etc.) from input workpiece supply102 to a support structure 106. Support structure 106 supports theworkpiece (now labelled as a clamped workpiece 102 a 2, when clampedagainst support structure 106 using a workpiece clamp 108, shown in FIG.5 ) during a welding operation. After the welding operation (describedbelow with respect to a weld head assembly 112), a now welded workpiece102 a 3 is moved (e.g., using a conveyor assembly, using a gripperassembly, etc.) from a portion of material handling system 104downstream of support structure 106, to an output workpiece supply 110.Output workpiece supply 110 is configured to receive welded workpieces102 a 3 after processing by weld head assembly 112 (where weld headassembly 112 includes an ultrasonic converter 112 b carrying a sonotrode202). Output workpiece supply 110 may be a carrier such as a magazinehandler for carrying a plurality of welded workpieces 102 a 3, oranother supply structure suitable for the application specificworkpiece.

Ultrasonic welding system 100 includes weld head assembly 112. Weld headassembly includes ultrasonic converter 112 b carrying a sonotrode 202,and is moveable along a plurality of substantially horizontal axes. Inthe example shown in FIG. 1 , weld head assembly 112 is configured tomove along the x-axis and the y-axis of ultrasonic welding system 100.In the example shown in FIG. 1 , weld head assembly 112 is alsoconfigured to move along the z-axis of ultrasonic welding system 100,and about a theta axis (Ø-axis) of ultrasonic welding system 100. Notall of these motion axes are required in each application. Using themotion axes of weld head assembly 112, sonotrode 202 is able to be movedinto proper welding positions with respect to clamped workpiece 102 a 2.Camera 114 is also provided (where camera may optionally be carried byweld head assembly 112, or may be carried by another part of ultrasonicwelding system 100) for imaging operations related to the alignmentbetween sonotrode 202 and clamped workpiece 102 a 2, the alignment ofthe components of clamped workpiece 102 a 2 in itself, opticalinspection of the welds after welding operation, etc.

Various types of workpieces may be welded using ultrasonic weldingsystem 100 (or other systems within the scope of the invention).Exemplary workpieces include a power module, a lead frame and a batterymodule.

Various types of ultrasonic motion may be imparted on a conductor (e.g.,a conductive pin, a signal connector, a conductive terminal, a powerterminal, etc.) in accordance with the invention. For example, thesonotrode may be configured to weld a conductor to a workpiece using atleast one of linear ultrasonic motion and torsional ultrasonic motion.

Certain of those workpieces are configured to receive a conductive pin.As used herein, the term “conductive pin” is a conductive structureintended to be welded to a workpiece. The conductive pin may have a freeend (after being welded to a workpiece), and a body portion of theconductive pin may extend substantially vertically from a “welded” endto the free end. The cross section of the conductive pin may be round,square, rectangular, or have any desired cross section. The termconductive pin shall also be construed to include conductive receptaclesor sleeves (e.g., a tubular shape), where the conductivereceptacle/sleeve is ultrasonically welded to a workpiece, andconfigured to receive another conductive element. In accordance withcertain exemplary embodiments of the invention, ultrasonic weldingsystem 100 includes a conductive pin supply 200 configured to provide aplurality of conductive pins for welding using sonotrode 202. Exemplaryconfigurations for conductive pin supply include: a grid arrangement(including columns and rows of conductive pins, oriented in such a wayfor ease of pick up), a bowl feeder, a hopper, a spool, etc. Alternativeconfigurations are contemplated. The conductive pin supply 200 may beconfigured to operate with a buffer system so that pins are fed througha staging area, ready to be picked up for welding.

Ultrasonic welding system 100, including conductive pin supply 200 andsonotrode 202, may take various forms. More specifically, differentconfigurations of conductive pin supply 200, different configurations ofsonotrode 202, etc. are contemplated. FIGS. 2A-2C illustrate anexemplary ultrasonic welding system 100 a, including an exemplaryconfiguration of the conductive pin supply (now referred to asconductive pin supply 200 a including conductive pins 200 a 1), and anexemplary configuration of the sonotrode (now referred to as sonotrode202 a defining a vacuum channel 202 a 1, and coupled to a vacuum source204 via piping 204 a). FIGS. 3A-3C illustrate an exemplary ultrasonicwelding system 100 b, including another exemplary configuration of theconductive pin supply (now referred to as conductive pin supply 200 bincluding conductive pins 200 b 1), and an exemplary configuration ofthe sonotrode (now referred to as sonotrode 202 b, adapted to work witha gripper actuator 206 and a gripper arm 206 a). FIG. 4 illustrates yetanother exemplary ultrasonic welding system 100 c, which issubstantially similar to ultrasonic welding system 100 b (in FIGS.3A-3C), except that ultrasonic welding system 100 c includes a gripperactuator 208, a first gripper arm 208 a, and a second gripper arm 208 b.Except as described herein, each of ultrasonic welding systems 100 a,100 b, and 100 c are substantially similar to ultrasonic welding system100 described above.

Referring specifically, to FIGS. 2A-2C, sonotrode 202 a is configured towithdraw a conductive pin 200 a 1 from conductive pin supply 200 a, andweld head assembly 112 is configured to carry (through its variousmotion axes) the withdrawn conductive pin 200 a 1 towards clampedworkpiece 102 a 2, and to ultrasonically weld the conductive pin 200 a 1to clamped workpiece 102 a 2. Sonotrode 202 a defines a vacuum channel202 a 1 connected to vacuum source 204 via piping 204 a, for withdrawingthe conductive pin 200 a 1 from the conductive pin supply 200 a.

Referring specifically to FIG. 2B, a tip portion 202 a 3 of sonotrode202 is shown. Vacuum channel 202 a 1 is defined by sonotrode 202 a. Aworking surface 202 a 2 of sonotrode 202 a is configured to contact aweld portion of a conductive pin and press it against to a workpiece forultrasonic welding (e.g., see weld portion of conductive pin shown inFIG. 2C). A vacuum hole 202 a 4 of sonotrode 202 a (configured forengagement with piping 204 a as shown in FIG. 2A) is also illustrated.FIG. 2C is a side view of conductive pin 200 a 1 (e.g., a roundconductive pin) including a body portion 200 a 1 a, a weld portion 200 a1 b, and a free end 200 a 1 c. After being welded to a workpiece viaweld portion 200 a 1 b, body portion 200 a 1 a may extend substantiallyvertically from weld portion 200 a 1 b to free end 200 a 1 c. Free end200 a 1 c (or some other portion of welded conductive pin 200 a 1) isavailable for an electrical connection as needed in the given workpiece.

Referring specifically to FIGS. 3A-3C, weld head assembly 112 includes agripper mechanism configured to withdraw a conductive pin 200 b 1 from aconductive pin supply 200 b. In FIG. 3A, the gripper mechanism includesa gripper actuator 206 and a moveable arm 206 a. Through actuation ofgripper actuator 206, moveable arm 206 a is configured to move between(i) an open position as shown in FIG. 3B for engaging the conductive pin200 b 1 and (ii) a closed position as shown in FIG. 3C for holding theconductive pin 200 b 1 in a position for motion toward the clampedworkpiece 102 a 2. As shown in FIG. 3B, moveable arm 206 a aligns theconductive pin 200 b 1 with the sonotrode 202 b in the closed position,holding the conductive pin 200 b 1 in place with respect to sonotrode202 b. Weld head assembly 112 is configured to carry the withdrawnconductive pin 200 b 1 towards the workpiece, and to ultrasonically weldthe conductive pin 200 b 1 to the clamped workpiece 102 a 2.

Referring specifically to FIG. 4 , weld head assembly 112 includesanother gripper mechanism configured to withdraw a conductive pin 200 b1 from the conductive pin supply 200 b. In FIG. 4 , the grippermechanism includes a gripper actuator 208, a moveable arm 208 a, and astationary arm 208 b. Through actuation of gripper actuator 208,moveable arm 208 a is configured to move between (i) an open positionfor engaging the conductive pin 200 b 1 and (ii) a closed position forholding the conductive pin 200 b 1 in a position for motion toward theclamped workpiece 102 a 2. As shown in FIG. 4 , moveable arm 208 a movesto secure conductive pin 200 b 1 in place against the stationary arm 208b in the closed position, thereby aligning the conductive pin 200 b 1with sonotrode 202 b. Weld head assembly 112 is configured to carry thewithdrawn conductive pin 200 b 1 towards the clamped workpiece 102 a 2,and to ultrasonically weld the conductive pin 200 b 1 to the clampedworkpiece 102 a 2.

Referring specifically conductive pin 200 b 1 shown in FIGS. 3A-3C andFIG. 4 , and detailed in FIG. 3D, conductive pin 200 b 1 has a differentconfiguration as compared to conductive pin 200 a 1 from FIGS. 2A-2C.Conductive pin 200 b 1 includes body portion 200 b 1 a, weld portion 200b 1 b, and free end 200 b 1 c. After being welded to a workpiece viaweld portion 200 b 1 b, body portion 200 b 1 a may extend substantiallyvertically from weld portion 200 b 1 b to free end 200 b 1 c. Free end200 b 1 c (or some other portion of welded conductive pin 200 b 1) isavailable for an electrical connection as needed in the given workpiece.

It will be appreciated that while aspects of the invention specificallyrelate to ultrasonic welding systems for welding conductive pins to aworkpiece, it is not limited thereto. For example, in accordance withcertain exemplary embodiments of the invention, the sonotrode isconfigured for welding the conductive pin to the workpiece, and forwelding other conductors (e.g., a conductive terminal such as a powerterminal) to the workpiece. The sonotrode may use a single working area(e.g., such as working surface 202 a 2 shown in FIG. 2B) to weld bothconductive pins and other conductors such as power terminals. However,in other embodiments of the invention, the sonotrode includes a firstarea configured for contacting the conductive pin for welding to theworkpiece, and a second area for contacting a power terminal for weldingto the workpiece.

In other exemplary embodiments of the invention, the ultrasonic weldingsystem includes a second weld head assembly having a second ultrasonicconverter carrying a second sonotrode, the second weld head assemblyconfigured for welding power terminals to the workpiece. Referringspecifically to FIG. 5 , an ultrasonic welding system 500 is shown.Ultrasonic welding system 500 includes a first ultrasonic weldingsubsystem 502 (which may be substantially similar to ultrasonic weldingsystem 100 shown in FIG. 1 of International Publication No. 2018/187364,and is also similar to welding systems disclosed herein except thatfirst ultrasonic welding subsystem 502 includes a sonotrode 112 a anddoes not include a conductive pin supply) and a second ultrasonicwelding subsystem 504. Second ultrasonic welding subsystem 504 may be,for example, ultrasonic welding system 100 shown in FIG. 1 , ultrasonicwelding system 100 a shown in FIG. 2A, ultrasonic welding system 100 bshown in FIG. 3A, ultrasonic welding system 100 c shown in FIG. 4 ,among others. First ultrasonic welding subsystem 502 is configured toweld certain conductors (e.g., larger power conductors such as powerterminals 506), while second ultrasonic welding subsystem 504 isconfigured to weld conductive pins as herein. FIG. 5 shows an example ofan output workpiece 102 a 3′ of ultrasonic welding system 500. Outputworkpiece 102 a 3′ includes a substrate (not labelled), a conductiveterminal 506 ultrasonically welded to the substrate, and a conductivepin 200 a 1 ultrasonically welded to the substrate. For example,workpiece 102 a 3′ may be a power semiconductor module where conductiveterminal 506 is a power terminal of the power semiconductor module, andwhere conductive pin 200 a 1 is a signal connection of the powersemiconductor module.

While FIG. 5 illustrates a conductive pin supply 200 a includingconductive pins 200 a 1 (i.e., similar to the configuration in FIG. 2A),the inventive features of ultrasonic welding system 500 (includingultrasonic welding system 504) may be applied to any type of conductivepins within the scope of the invention (e.g., conductive pin 200 b 1shown in FIG. 3A), along with corresponding changes to the weld headassembly.

According to certain exemplary embodiments of the invention, during thewelding operations, exemplary technical specifications include: (i) thesonotrode being configured to operate at a bond force of between 5-500kg, or the sonotrode being configured to operate at a bond force ofbetween 5-300 kg, or the sonotrode being configured to operate at a bondforce of between 5-100 kg; (ii) the sonotrode tip motion amplitude beingbetween 5-150 microns, or the sonotrode tip motion amplitude beingbetween 5-120 microns, or the sonotrode tip motion amplitude beingbetween 5-100 microns; (iii) the sonotrode being configured to form anultrasonic weld between a first portion of a workpiece and a secondportion of a workpiece having an area in a range between 1.5-30 mm²; orthe sonotrode being configured to form an ultrasonic weld between afirst portion of a workpiece and a second portion of a workpiece havingan area in a range between 1.5-20 mm²; or the sonotrode being configuredto form an ultrasonic weld between a first portion of a workpiece and asecond portion of a workpiece having an area in a range between 1.5-16mm²; and (iv) the sonotrode being configured to operate at a frequencyin a range between 15-40 kHz, or the sonotrode being configured tooperate at a frequency in a range between 20-35 kHz, or the sonotrodebeing configured to operate at a frequency in a range between 20-30 kHz.Exemplary thicknesses of the conductive contact of the contact element(the part of the workpiece being contacted by the sonotrode) include:between 0.2-3 mm; 0.2-1.5 mm, and 0.2-1.2 mm.

Variations within the scope of the invention are contemplated, even ifnot illustrated. For example, in accordance with certain exemplaryembodiments of the invention, the weld head assembly may define a keyingfeature configured to align with a corresponding keying feature of theconductive pins such that a conductive pin held by the weld headassembly is properly aligned with respect to the sonotrode. FIGS. 6A-6Dand FIGS. 6E-6G illustrate examples of such embodiments of theinvention. The conductive pins and sonotrodes of FIGS. 6A-6D and FIGS.6E-6G may be implemented in connection with any of the ultrasonicwelding systems disclosed herein (e.g., ultrasonic welding systems 100,100 a, 100 b, 100 c, 504, and 700), or any other ultrasonic weldingsystem within the scope of the invention.

FIGS. 6A and 6B are, respectively, side and top views of a conductivepin 600 a 1 (e.g., a round conductive pin) including a body portion 600a 1 a, a weld portion 600 a 1 b, a free end 600 a 1 c, and a keyingfeature 600 a 1 d. Keying feature 600 a 1 d of conductive pin 600 a 1may be used to align with a corresponding keying feature of weld headassembly (e.g., a keyway) such that conductive pin 600 a 1 held by weldhead assembly is properly aligned with respect to sonotrode 602 a. Afterbeing welded to a workpiece via weld portion 600 a 1 b, body portion 600a 1 a may extend substantially vertically from weld portion 600 a 1 b tofree end 600 a 1 c. Free end 600 a 1 c (or some other portion of weldedconductive pin 600 a 1) is available for an electrical connection asneeded in the given workpiece. FIG. 6C is an end view of sonotrode 602a, including a vacuum channel 602 a 1 defined by sonotrode 602 a. Atvacuum channel 602 a 1, sonotrode 602 a defines a keying feature 602 a 1d (e.g., a recess). When conductive pin 600 a 1 is engaged withsonotrode 602 a, keying feature 600 a 1 d engages with keying feature602 a 1 d. FIG. 6D shows conductive pin 600 a 1 aligned with respect tosonotrode 602 a of a weld head assembly (not shown, but see weld headassembly 112 throughout the various drawings).

FIGS. 6E and 6F are, respectively, side and top views of a conductivepin 600 b 1 (e.g., a conductive pin having an “L” shape) including abody portion 600 b 1 a, a weld portion 600 b 1 b, a free end 600 b 1 c,and a keying feature 600 b 1 d (e.g., a protrusion). Keying feature 600b 1 d of conductive pin 600 b 1 may be used to align with acorresponding keying feature (e.g., a keyway) of gripper arm 206 a′(similar to gripper arm 206 a of FIGS. 3A-3C) such that conductive pin600 b 1 is held in place by gripper arm 206 a′ of weld head assembly,thereby aligning conductive pin 600 b 1 with respect to sonotrode 602 a.After being welded to a workpiece via weld portion 600 b 1 b, bodyportion 600 b 1 a may extend substantially vertically from weld portion600 b 1 b to free end 600 b 1 c. Free end 600 b 1 c (or some otherportion of welded conductive pin 600 b 1) is available for an electricalconnection as needed in the given workpiece. FIG. 6G is a top view ofgripper arm 206 a′ engaged with conductive pin 600 b 1. Gripper arm 206a′ defines a keying feature 206 a′1 (i.e., a recess). When conductivepin 600 b 2 is engaged with gripper arm 206 a′, keying feature 206 a′1engages with keying feature 602 b 1 d.

The keying features illustrated and described in connection with FIG.6A-6G are exemplary in nature; alternative keying features or alignmentfeatures are contemplated within the scope of the invention. Forexample, keying feature 600 a 1 d protrudes from body portion 600 a 1 aof conductive pin 600 a 1; however, a recessed keying feature may beutilized in connection with such a conductive pin, where a mating keyingfeature of a sonotrode (or other portion of a bond head assembly) may bea protruding feature.

Further, in accordance with certain exemplary embodiments of theinvention, the sonotrode (or other aspect of the weld head assembly suchas a gripper mechanism) may not act as a pick tool. Rather, theultrasonic welding system may further include a pick tool configured towithdraw a conductive pin from the conductive pin supply, where thewithdrawn conductive pin is transferred to the weld head assembly forwelding to the workpiece.

Referring specifically to FIG. 7 , ultrasonic welding system 700 isshown. Ultrasonic welding system 700 (which is similar to the previouslydetailed ultrasonic welding systems described herein) includes a picktool 702. Pick tool 702 includes a contact portion 702 a. In accordancewith certain exemplary embodiments of the invention, pick tool 702withdraws (or otherwise receives) conductive pin 200 a 1 from conductivepin supply 200 a. The conductive pin 200 a 1 is transferred to weld headassembly 112 for welding to workpiece 102 a 2. Contact portion 702 a mayhave a number of different alternative configurations for pickingconductive pin 200 a 1 from conductive pin supply 200 a, and engaging intransferring conductive pin 200 a 1 to sonotrode 202 a of weld headassembly 112. Exemplary configurations of contact portion 702 a include:a magnetic holding mechanism; a mechanical gripping mechanism; a vacuumbased holding mechanism; among others.

Referring again to FIG. 7 , once pick tool 702 holds a conductive pin200 a 1, pick tool 702 may move toward sonotrode 202 a for transfer ofthe conductive pin 200 a 1 (see dotted line portion of conductive pin200 a 1 engaged with sonotrode 202 a). Alternatively, sonotrode 202 a(carried by weld head assembly 112) may be moved toward pick tool 702for transfer of the conductive pin 200 a 1. In yet another alternative,both pick tool 702 and sonotrode 202 a may be moved towards one anotherfor transfer of the conductive pin 200 a 1. While FIG. 7 illustrates aconductive pin supply 200 a including conductive pins 200 a 1 (i.e.,similar to the configuration in FIG. 2A), the inventive features ofultrasonic welding system 700 may be applied to any type of conductivepins within the scope of the invention (e.g., conductive pin 200 b 1shown in FIG. 3A), along with corresponding changes to the weld headassembly.

Although the invention is illustrated and described herein withreference to specific embodiments, the invention is not intended to belimited to the details shown. Rather, various modifications may be madein the details within the scope and range of equivalents of the claimsand without departing from the invention.

What is claimed:
 1. An ultrasonic welding system comprising: a supportstructure configured for supporting a workpiece; a weld head assemblyincluding an ultrasonic converter carrying a sonotrode; and a conductivepin supply configured to provide a plurality of conductive pins forwelding using the sonotrode, wherein the weld head assembly includes agripper mechanism configured to withdraw a conductive pin from theconductive pin supply, and the weld head assembly is configured to carrythe withdrawn conductive pin towards the workpiece, and toultrasonically weld the conductive pin to the workpiece, wherein thegripper mechanism includes a moveable arm configured to move between (i)an open position for engaging the conductive pin and (ii) a closedposition for holding the conductive pin in a position for motion towardthe workpiece.
 2. The ultrasonic welding system of claim 1 wherein theweld head assembly is configured to move along a plurality of distinctmotion axes.
 3. The ultrasonic welding system of claim 2 wherein theplurality of distinct motion axes includes an x-axis, a y-axis, and az-axis.
 4. The ultrasonic welding system of claim 2 wherein theplurality of distinct motion axes includes a theta axis.
 5. Theultrasonic welding system of claim 1 wherein the moveable arm aligns theconductive pin with the sonotrode in the closed position.
 6. Theultrasonic welding system of claim 1 wherein the gripper mechanismfurther includes a stationary arm, wherein the moveable arm aligns theconductive pin with the sonotrode in the closed position.
 7. Theultrasonic welding system of claim 1 wherein the weld head assemblydefines a keying feature configured to align with a correspondingfeature of the conductive pins such that the conductive pin held by theweld head assembly is properly aligned with respect to the sonotrode. 8.The ultrasonic welding system of claim 1 further comprising a pick toolconfigured to withdraw a conductive pin from the conductive pin supply,the withdrawn conductive pin being transferred to the weld head assemblyfor welding to the workpiece.
 9. The ultrasonic welding system of claim1 wherein the sonotrode is configured for welding the conductive pin tothe workpiece, and for welding a power terminal to the workpiece. 10.The ultrasonic welding system of claim 1 wherein the sonotrode includesa first area configured for contacting the conductive pin for welding tothe workpiece, and a second area for contacting a power terminal forwelding to the workpiece.
 11. The ultrasonic welding system of claim 1further comprising a second weld head assembly including a secondultrasonic converter carrying a second sonotrode, the second weld headassembly configured for welding power terminals to the workpiece.
 12. Amethod of operating an ultrasonic welding system, the method comprisingthe steps of: supporting a workpiece on a support structure of theultrasonic welding system; and welding a conductive pin from aconductive pin supply of the ultrasonic welding system to the workpieceusing a sonotrode of a weld head assembly of the ultrasonic weldingsystem, the conductive pin supply including a plurality of theconductive pins, wherein the weld head assembly includes a grippermechanism, and the method further comprises the steps of (i) withdrawingthe conductive pin from the conductive pin supply using the grippermechanism, and (ii) carrying the withdrawn conductive pin towards theworkpiece using the weld head assembly, wherein the gripper mechanismincludes a moveable arm configured to move between (i) an open positionfor engaging the conductive pin and (ii) a closed position for holdingthe conductive pin in a position for motion toward the workpiece. 13.The method of claim 12 wherein the weld head assembly is configured tomove along a plurality of distinct motion axes of the ultrasonic weldingsystem.
 14. The method of claim 13 wherein the plurality of distinctmotion axes includes an x-axis, a y-axis, and a z-axis.
 15. The methodof claim 13 wherein the plurality of distinct motion axes includes atheta axis.
 16. The method of claim 12 wherein the moveable arm alignsthe conductive pin with the sonotrode in the closed position.
 17. Themethod of claim 12 wherein the gripper mechanism further includes astationary arm, wherein the moveable arm aligns the conductive pin withthe sonotrode in the closed position.
 18. The method of claim 12 whereinthe weld head assembly defines a keying feature configured to align witha corresponding feature of the conductive pins such that the conductivepin held by the weld head assembly is properly aligned with respect tothe sonotrode.
 19. The method of claim 12 further comprising the stepsof (i) withdrawing the conductive pin from the conductive pin supplyusing a pick tool, and (ii) transferring the conductive pin from thepick tool to the weld head assembly for welding to the workpiece. 20.The method of claim 12 further comprising the step of welding a powerterminal to the workpiece using the sonotrode.
 21. The method of claim20 wherein the sonotrode includes a first area configured for contactingthe conductive pin for welding to the workpiece, and a second area forcontacting the power terminal for welding to the workpiece.
 22. Themethod of claim 12 wherein the ultrasonic welding system includes asecond weld head assembly including a second ultrasonic convertercarrying a second sonotrode, the method further comprising the step ofwelding a power terminal to the workpiece using the second sonotrode.